单壁碳纳米管冲击吸能特性分析

碳纳米管的优异力学特性使其在冲击能量吸收方面存在潜在的应用前景,但纳米尺度的冲击验证实验却难以实现.应用分子结构力学、冲击动力学和纳米尺度有限元相结合的方法,研究了单壁碳纳米管受轴向冲击的吸能特性.使用ANSYS中APDL编程语言,建立了单壁碳纳米管的空间结构参数化模型;同时,采用修正的Morse原子势函数拟合了C-C共价键的本构方程.按照最大失效应变作为共价键断裂的判据,对比了长度、直径和手性对单壁碳纳米管冲击吸能的影响.结果表明:采用这种仿真方法可以动态呈现碳纳米管断裂的全过程,且能够证实单壁碳纳米管的比吸能远高于其他材质类似管状结构,其中,锯齿型碳纳米管的吸能特性又好于扶手椅型.

Impact energy absorption characteristics of Single-walled carbon nanotubes

The excellent mechanics characteristics of carbon nanotubes make them potentially applicated in energy absorption, however, it is still difficult to be verified by nano-scale experiments. By integrating the principle of molecular structural mechanics into the nano-scale finite element method, the fracture process of single-walled carbon nanotubes(SWCNTs)under axial impact loads was simulated based on the principle of impact dynamics. The parametric structural model of SWCNTs was built by APDL language in ANSYS software. Meanwhile, the constitutive equation of C-C bond was obtained by the modified Morse potential function. According to the failure strain criterion, the energy absorption capability of SWCNTs with different diameter, length and chiral was investigated. The proposed simulation method can effectively predict the locations and directions of fracture in SWCNTs, and the growth process of rupture could also be visualized dynamically. It is demonstrated that the specific energy absorption of SWCNTs is much higher than that of similar tubes manufactured by other materials. In addition, the energy absorption of zigzag SWCNTs is higher than that of the armchair SWCNTs.